Ophthalmologic imaging apparatus and ophthalmologic imaging method

ABSTRACT

An opthalmologic imaging apparatus that captures a fundus image of a subject&#39;s eye includes a first extraction unit configured to extract, from a first fundus image photographed with a first light quantity, an image of a first area having intensity not less than predetermined intensity and an image of a second area other than the first area, a second extraction unit configured to extract an image of an area corresponding to the first area from a second fundus image photographed with a second light quantity based on the light quantity of the first area, a third extraction unit configured to extract an image of an area corresponding to the second area from a third fundus image photographed with a third light quantity based on the light quantity of the second area, and an image combining unit configured to combine the images extracted by the second and the third extraction units.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an opthalmologic imaging apparatus andan opthalmologic imaging method that captures a fundus of a subject'seye.

2. Description of the Related Art

Japanese Patent Application Laid-Open No. 2000-107133 discusses a funduscamera that can photograph a fundus by adequately shading a brightportion and a dark portion of the fundus within a photographing field ofview, even if an exposure condition is unclear. This is a technique ofcausing a photographing light source to emit a strong light and a weaklight alternately, when a fundus is subjected to fluorescencephotography, since fluorescent intensity is significantly differentbetween a thick blood vessel and a thin blood vessel.

Japanese Patent Application Laid-Open No. 2003-10134 discusses a funduscamera that can illuminate only an optic papilla with a visible light toadjust focusing in the optic papilla without contracting a pupil of asubject's eye.

However, Japanese Patent Application Laid-Open No. 2000-107133 does notdiscuss that a quantity of emitted light is adjusted according to aportion to be photographed, when the photographing light source isallowed to emit a strong light and a weak light. Further, the imageobtained in Japanese Patent Application Laid-Open No. 2003-10134 is nota fundus image in which both the optic papilla and the portion otherthan the optic papilla are brought into focus, so that the image has aninsufficient image quality for diagnosis.

It is considered here that an optic papilla and a macula aresimultaneously photographed as a single fundus image, when the fundus isphotographed. When the optic papilla is properly exposed, the macula istotally underexposed. On the contrary, when the macula is properlyexposed, the optic papilla is totally overexposed. This is because theoptic papilla is the brightest, and the macula is the darkest in thephotographing field of view of the fundus, and a dynamic range of animage sensor is insufficient to simultaneously photograph both portions.

It is then considered the case in which the optic papilla isphotographed with a visible light, while the macula is photographed withan infrared light, and then, both images are combined to form a fundusimage. In this case, the combined image has an insufficient imagequality for diagnosis, since these two images are not photographed withthe same light quantity.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, an opthalmologicimaging apparatus that captures an image of a fundus of a subject's eyeincludes a first extraction unit configured to extract, from a firstfundus image photographed with a first light quantity, an image of afirst area having intensity not less than predetermined intensity and animage of a second area other than the first area, a second extractionunit configured to extract an image of an area corresponding to thefirst area from a second fundus image photographed with a second lightquantity based on the light quantity of the first area, a thirdextraction unit configured to extract an image of an area correspondingto the second area from a third fundus image photographed with a thirdlight quantity based on the light quantity of the second area, and animage combining unit configured to combine the images extracted by thesecond and the third extraction units.

According to another aspect of the present invention, a method for anopthalmologic imaging to capture an image of a fundus of a subject's eyeincludes a first extracting step for extracting, from a first fundusimage photographed with a first light quantity, an image of a first areahaving intensity not less than predetermined intensity and an image of asecond area other than the first area, a second extracting step forextracting an image of an area corresponding to the first area from asecond fundus image photographed with a second light quantity based onthe light quantity of the first area, a third extracting step forextracting an image of an area corresponding to the second area from athird fundus image photographed with a third light quantity based on thelight quantity of the second area, and a combining step for combiningthe images which are extracted in the second and third extracting steps.

According to the opthalmologic imaging apparatus and the opthalmologicimaging method according to the present invention, areas (mainly, anarea including an optic papilla and another area including a lutea)having different brightness in a fundus of a subject's eye can bephotographed with a proper light quantity. When these images arecombined, a fundus image having an image quality sufficient fordiagnosis can be acquired.

Further features and aspects of the present invention will becomeapparent from the following detailed description of exemplaryembodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate exemplary embodiments, features,and aspects of the invention and, together with the description, serveto explain the principles of the invention.

FIG. 1 illustrates a configuration of a fundus camera according to afirst exemplary embodiment of the present invention.

FIG. 2 is an enlarged side view of a focus index projection unit.

FIG. 3 is an enlarged front view of the focus index projection unit.

FIGS. 4A to 4C illustrate a state in which a focus index light fluxreaches a fundus of a subject's eye, and a focus index image on thefundus by the focus index light flux.

FIG. 5 illustrates a display screen of a display unit according to thefirst exemplary embodiment.

FIG. 6 is a flow chart illustrating an operation of a calculation unitaccording to the first exemplary embodiment.

FIGS. 7A to 7G illustrate a method for detecting an optic papilla N of afundus, and a method for combining images according to the firstexemplary embodiment.

FIGS. 8A to 8C are histograms of fundus image data.

FIG. 9 illustrates a configuration of a fundus camera according to asecond exemplary embodiment.

FIG. 10 is a flow chart illustrating an operation of a calculation unitaccording to the second exemplary embodiment.

FIGS. 11A to 11E illustrate a method for combining fundus imagesaccording to the second exemplary embodiment.

DESCRIPTION OF THE EMBODIMENTS

Various exemplary embodiments, features, and aspects of the inventionwill be described in detail below with reference to the drawings.

Exemplary embodiments of an opthalmologic imaging apparatus and anopthalmologic imaging method according to the present invention will bedescribed in detail below with reference to the drawings.

FIG. 1 illustrates a configuration of a fundus camera according to afirst exemplary embodiment. An observation light source 3 including ahalogen lamp, a condenser lens 4, a photographing light source 5including a xenon tube, and a mirror 6 are arranged on an optical pathO1 of an illumination optical system from a reflector 1 to an objectivelens 2 located opposite to a subject's eye E. A diaphragm 7 having anring shaped opening, a relay lens 8, a focus index projection unit 9, arelay lens 10, and a perforated mirror 11 are sequentially arranged in areflecting direction of the mirror 6.

A focusing lens 12, a photographic lens 13, a three-color wavelengthseparation unit 14 a, and an imaging unit 14 including an image sensor14 b are sequentially arranged on an optical path O2 of anobservation/photographing optical system at the rear of the perforatedmirror 11. The focus index projection unit 9 and the focusing lens 12are moved in conjunction with each other by a focus link mechanism 15.

An output of the imaging unit 14 is connected to a control unit 22 thatcontrols a photographing operation via an image signal processing unit21, and an output of the image signal processing unit 21 is connected toa display unit 23 that displays an image. An output of the control unit22 is connected to the observation light source 3, the photographinglight source 5, and the focus index projection unit 9 respectively viaan observation light source driving circuit 24, a photographing lightsource driving circuit 25, and a focus index control circuit 26. Aninput unit 27 and a recording unit 28 are also connected to the controlunit 22.

FIG. 2 is an enlarged side view of the focus index projection unit 9.FIG. 3 is an enlarged front view of the focus index projection unit 9.The focus index projection unit 9 includes a focus split prism havingprism portions 9 a, 9 b, and 9 c, a focus index 9 d having a rectangularopening, and a focus index light source 9 e. The prism portions 9 b and9 c have prism surfaces whose angles are symmetric with each other. Thefocus index light source 9 e includes a light-emitting diode (LED)having a center wavelength in a visible light.

The focus index projection unit 9 moves in a direction A indicated inFIG. 1 in conjunction with the focusing lens 12 by the focus linkmechanism 15, so that the focus index 9 d of the focus index projectionunit 9 and the image sensor 14 b of the imaging unit 14 have an opticalconjugate relation. When a still image is photographed, the focus indexprojection unit 9 rotates about an axis 9 f to move in the direction Bin FIG. 1, thereby retracting from the optical path O1 of theillumination optical system.

During the observation of a fundus, a light flux emitted from theobservation light source 3 passes through the condenser lens 4, themirror 6, the diaphragm 7, the relay lens 8, the focus index projectionunit 9, and the relay lens 10 and reflected around the perforated mirror11. Further, the light flux illuminates a fundus Er through a cornea Ecand a pupil Ep of the subject's eye E via the objective lens 2. Thecontrol unit 22 controls the focus index control circuit 26 to turn onthe focus index light source 9 e of the focus index projection unit 9.

As illustrated in FIG. 2, the light flux from the focus index lightsource 9 e is polarized in the direction of the optical path O1 by theprism portion 9 a of the focus split prism, reaches the prism portions 9b and 9 c, and is branched in two directions. The light flux furtherpasses through the rectangular opening of the focus index 9 d to becometwo focus index light fluxes Lb and Lc which are symmetric with eachother to the optical path O1 and reaches the fundus Er of the subject'seye E via the relay lens 10, the perforated mirror 11, and the objectivelens 2.

Each of FIGS. 4A to 4C illustrates a state in which the focus indexlight fluxes Lb and Lc reach the fundus Er, and focus index images Fband Fc on the fundus Er formed by the focus index light fluxes Lb andLc. FIG. 4A illustrates the case in which the fundus Er and the focusindex 9 d are in an optical conjugate relation. Since the fundus Er andthe focus index 9 d are in the optical conjugate relation, the twoseparated focus index light fluxes Lb and LC form the images Fb and Fcof the rectangular opening of the focus index 9 d on the fundus Er, andthey are arranged side by side.

FIG. 4B illustrates the case in which the subject's eye E is myopic morethan the case in FIG. 4A. Since the fundus Er and the focus index 9 dare not in the optical conjugate relation, the two separated focus indexlight fluxes Lb and Lc form the images Fb and Fc of the rectangularopening of the focus index 9 d on the fundus Er, and they are shiftedfrom each other in a vertical direction, wherein the image Fb is shiftedupward and the image Fc is shifted downward.

FIG. 4C illustrates the case in which the subject's eye E is hyperopicmore than the case in FIG. 4A. Since the fundus Er and the focus index 9d are not in the optical conjugate relation, the two separated focusindex light fluxes Lb and Lc form the images Fb and Fc of therectangular opening of the focus index 9 d on the fundus Er, and theyare shifted from each other in the vertical direction, wherein the imageFb is shifted downward and the image Fc is shifted upward.

An illuminated fundus image Er′ and the index images Fb and Fc passesthrough the pupil Ep, a cornea Ec, the objective lens 2, and holes ofthe perforated mirror 11, the focusing lens 12, and the photographiclens 13, reaches the image sensor 14 b via the three-color wavelengthseparation unit 14 a in the imaging unit 14, and form images thereon.

The image sensor 14 b performs a photoelectric conversion to the fundusimage Er′ as a reflected image of the fundus Er, and the focus indeximages Fb and Fc. The image signal processing unit 21 reads data fromthe image sensor 14 b, and performs amplification and A/D conversion onthe data, so that digital image data is generated. The generated digitalimage data is input to the control unit 22, and simultaneously,displayed on the display unit 23 as a moving image as illustrated inFIG. 5.

An operator observes the index images Fb and Fc of the rectangularopening of the focus index 9 d displayed on the display unit 23, andoperates a focus knob to arrange the focus images Fb and Fc side byside. More specifically, when the fundus Er and the focus index 9 d arein the optical conjugate relation, the focus index 9 d of the focusindex projection unit 9 and the image sensor 14 b are in an opticalconjugate relation by the focus link mechanism 15 (a unit which moves afirst moving unit configured to move the focus index projection unit anda second moving unit configured to move the focusing unit in conjunctionwith each other). Therefore, the fundus Er and the image sensor 14 b arebrought into an optical conjugate relation by moving from a firstconjugate position to a second conjugate position, so that the fundus Eris brought into focus.

FIG. 6 is a flow chart illustrating an operation when the fundus isphotographed. The operator adjust alignment and focus, while observingthe image illustrated in FIG. 5 which is displayed on the display unit23. When the alignment is matched and the image is brought into focus,the operator presses a photographing switch of the input unit 27. (Withthis operation, a first fundus image can be photographed with a firstlight quantity.) In step S1, the control unit 22 detects the operationthat the photographing switch is pressed. In step S2, the control unit22 controls the focus index control circuit 26 to drive the focus indexprojection unit 9 in the direction B to retract the same from theoptical path O1. In step S3, an optic papilla N (a first area) of thefundus Er is extracted (which is executed by a first extraction unit).

In general, the optic papilla N is the brightest part in the fundusimage. Therefore, the maximum value is selected from the digital imagedata of the fundus image of the fundus Er as illustrated in FIG. 7Awhich is obtained by the imaging unit 14 and input into the control unit22 via the image signal processing unit 21. For example, intensity(predetermined intensity) of 70% of the maximum value Dmax is defined asa reference value (which is executed by a setting unit). Then,binarization processing is performed with this reference value. FIG. 7Billustrates a result of the binarization processing. Among fundus imagedata pieces Dij, data having 0.7 or more of Dmax (having the intensitymore than the predetermined intensity) is defined to be 255, which isthe maximum value when the image data is 8 bits (0 to 255), and the datahaving less than 0.7 of Dmax is defined as 0 that corresponds to a blacksignal. In this way, the optic papilla N is extracted.

In step S4, the light quantity of the observation light source 3 (thelight source that emits light with first and second light quantities) ischanged by the observation light quantity control by the observationlight source driving circuit 24 in order that the optic papilla N in theimage in FIG. 7B extracted in step S3 has a proper light quantity(second light quantity based on the light quantity in the first area).In the present exemplary embodiment, the proper quantity is defined suchthat an average value Dav of the image data pieces Dij of the opticpapilla N is 120. In step S5, the image data as illustrated in FIG. 7Cin which the optic papilla N is properly exposed (a second fundus imagephotographed with the second light quantity) is recorded and stored inthe recording unit 28.

In step S6, the portions (the second area other than the first area) ofthe fundus Er excluding the optic papilla N extracted in step S3 isextracted (which is executed by the first extraction unit). In step S7,an emission amount of the photographing light source 5 (the light sourcethat emits light with a third light quantity) is calculated to make theportion other than the optic papilla N being properly exposed (a thirdlight quantity based on the light quantity in the second area). Further,in step S8, the observation light source driving circuit 24 iscontrolled to turn off the observation light source 3. In step S9, thecontrol unit 22 determines whether the imaging unit 14 is in arecordable state. When the imaging unit 14 is in the recordable state(YES in step S9), the processing proceeds to step S10 where the controlunit 22 allows the photographing light source 5 to emit light with thelight quantity (calculated result) calculated in step S7 insynchronization with the imaging unit 14 under photographing lightcontrol by the photographing light source driving circuit 25.

In step S11, the image of the fundus Er in which the portion other thanthe optic papilla N of the fundus Er is properly exposed (a third fundusimage photographed with the third light quantity) is recorded and storedin the recording unit 28. FIG. 7D illustrates image data which isobtained in this operation. In step S12, the optic papilla N isextracted (an image of an area corresponding to the first area isextracted from the second fundus image) from the image in FIG. 7C whichis recorded in step S5. FIG. 7E illustrates image data which is obtainedin this operation (which is executed by a second extraction unit). Instep S13, the portion other than the optic papilla N is extracted (animage of an area corresponding to the second area is extracted from thethird fundus image) from the image in FIG. 7D which is recorded in stepS11. FIG. 7F illustrates an image which is obtained in this operation(which is executed by a third extraction unit).

The observation light source 3 including the halogen lamp generally hasa color temperature of 3000 to 3400 K, while the photographing lightsource 5 including the xenon tube has a color temperature of 5500 to6000 K. The color temperatures of the respective light sources which areused to record the images in steps S5 and S11 are different, thus whenthe images recorded in steps S5 and S11 are combined without any change,an image having an unnatural color is formed. Accordingly, in step S14,two images are corrected to allow the image in FIG. 7E formed in stepS12 to have a color temperature equal to that of the image in FIG. 7Fwhich is photographed by the photographing light source 5.

In step S15, the images whose color temperatures are corrected in stepS14 are combined to form a single fundus image. FIG. 7G illustratesimage data which is obtained in this operation. The fundus image thusformed is exposed with proper exposure both at the optic papilla N andthe portion other than the optic papilla N which includes a macula M.

Each of FIGS. 8A to 8C illustrates a histogram of the image data for acombination of images executed in step S15 according to anotherexemplary embodiment. FIG. 8A is the histogram of the image data inwhich the optic papilla N of the fundus as illustrated in FIG. 7E isextracted. FIG. 8B is the histogram of the image data generated in stepS13 in which the portion other than the optic papilla N is extracted. Itis supposed that the image data has 8 bits (0 to 255), white isindicated by 255 that is the maximum value, and black is indicated by 0that is the minimum value. When the images are combined in step S15, theimage data may be extended to have 16 bits, the portion other than theoptic papilla N may be allocated to the lower 8 bits, and the opticpapilla N may be allocated to the higher 8 bits to perform the imagecombination. FIG. 8C illustrates the histogram when the images arecombined as described above. The images may be combined in such a mannerthat a blood vessel at the portion other than the optic papilla N and ablood vessel at the optic papilla N have the same brightness.

In the present exemplary embodiment, after the image of the opticpapilla N formed with using the observation light source 3 is recordedin steps S3 to S5, the image of the portion other than the optic papillaN formed with using the photographing light source 5 is recorded insteps S6 to S11. However, the order of recording may be different fromthe one described above. For example, after the processing in step S2 isexecuted, the processing in steps S6 to S11 are executed, and then, theprocessing in steps S3 to S5 are executed. Thereafter, the processingmay proceed to step S12.

FIG. 9 illustrates a configuration of a fundus camera according to asecond exemplary embodiment. In FIG. 9, the focus index projection unit9, the relay lens 10, and the focus link mechanism 15 are removed fromFIG. 1. The output of the control unit 22 is connected to the focusinglens 12 via the driving circuit 31.

FIG. 10 is a flow chart illustrating the operation of the control unit22 when a fundus is photographed. Compared to the flow chart illustratedin FIG. 6, in the flow chart in FIG. 10, step S2 is deleted, step S20for performing focusing control is added between steps S4 and S5, andstep S21 for moving the focusing lens is added between steps S7 and S8.

Steps S1, S3, and S4 are the same as those in the first exemplaryembodiment. In step S20, the driving circuit 31 is controlled to movethe focusing lens 12 in a direction of A in FIG. 9. From the fundusimage which is input into the control unit 22 via the image signalprocessing unit 21 and formed on the image sensor 14 b, the opticpapilla N is extracted in step S4. A focusing position at which theimage of the optic papilla N has the highest contrast is detected, andthe focusing lens 12 is stopped at the focusing position. In this way,the image of the fundus Er recorded in step S5 becomes the fundus imagein which the optic papilla N is properly exposed and brought into focusas illustrated in FIG. 11A.

Steps S5, S6, and S7 are the same as those in the first exemplaryembodiment. In step S21, the driving circuit 31 is controlled to movethe focusing lens 12 by a predetermined amount. From the fundus imagewhich is input into the control unit 22 via the image signal processingunit 21 and formed on the image sensor 14 b, the portion other than theoptic papilla N is extracted in step S6. The focusing lens 12 is stoppedat a position at which the portion other than the optic papilla N hasthe highest contrast. More specifically, the focusing lens 12 is movedby the predetermined amount that is a difference between the focusingposition of the optic papilla N and the focusing position of the portionother than the optic papilla N. In this way, the image of the fundus Errecorded in step S11 becomes the fundus image in which the portion otherthan the optic papilla N is properly exposed and brought into focus asillustrated in FIG. 11B.

Steps S8 to S15 are the same as those in the first exemplary embodiment.The image formed in step S13 as illustrated in FIG. 11C and the imageformed in step S14 as illustrated in FIG. 11D are combined to form asingle fundus image in step S15. This image is a fundus image in whichthe optic papilla N and the portion other than the optic papilla N andthat includes the macula M are properly exposed and brought into focusas illustrated in FIG. 11E.

Aspects of the present invention can also be realized by a computer of asystem or apparatus (or devices such as a CPU or MPU) that reads out andexecutes a program recorded on a memory device to perform the functionsof the above-described embodiment (s), and by a method, the steps ofwhich are performed by a computer of a system or apparatus by, forexample, reading out and executing a program recorded on a memory deviceto perform the functions of the above-described embodiment (s). For thispurpose, the program is provided to the computer for example via anetwork or from a recording medium of various types serving as thememory device (e.g., computer-readable medium).

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all modifications, equivalent structures, and functions.

This application claims priority from Japanese Patent Applications No.2009-162824 filed Jul. 9, 2009, and No. 2010-144217 filed Jun. 24, 2010,which are hereby incorporated by reference herein in their entirety.

1. An opthalmologic imaging apparatus that captures an image of a fundusof a subject's eye, the opthalmologic imaging apparatus comprising: afirst extraction unit configured to extract, from a first fundus imagephotographed with a first light quantity, an image of a first areahaving intensity not less than predetermined intensity and an image of asecond area other than the first area; a second extraction unitconfigured to extract an image of an area corresponding to the firstarea from a second fundus image photographed with a second lightquantity based on the light quantity of the first area; a thirdextraction unit configured to extract an image of an area correspondingto the second area from a third fundus image photographed with a thirdlight quantity based on the light quantity of the second area; and animage combining unit configured to combine the images extracted by thesecond and the third extraction units.
 2. The opthalmologic imagingapparatus according to claim 1, wherein the first fundus image is animage including an optic papilla and a lutea of the fundus, and theopthalmologic imaging apparatus further comprising a setting unitconfigured to set the predetermined intensity to allow the first area tobecome the area corresponding to the optic papilla of the fundus.
 3. Theopthalmologic imaging apparatus according to claim 1, furthercomprising: an observation light source that emits light having thefirst and the second light quantities; a photographing light source thatemits light having the third light quantity; a calculation unitconfigured to calculate the second light quantity to allow the lightquantity at the first area to become a proper light quantity, andcalculate the third light quantity to allow the light quantity at thesecond area to become a proper light quantity; and a control unitconfigured to control the observation light source and the photographinglight source according to a result of the calculation by the calculationunit.
 4. The opthalmologic imaging apparatus according to claim 3,wherein the combination of the images is performed in such a way thatimages in which a difference between color temperature of theobservation light source and color temperature of the photographinglight source is corrected are combined.
 5. The opthalmologic imagingapparatus according to claim 1, further comprising: a focusing unitconfigured to focus returning light from the fundus on the imaging unit;and a moving unit configured to move the focusing unit to a position atwhich the fundus and the imaging unit are conjugate with each other,wherein the second fundus image including the optic papilla of thefundus and the third fundus image including the lutea of the fundus arephotographed at the different positions.
 6. An opthalmologic imagingapparatus that captures an image of a subject's eye, the opthalmologicimaging apparatus comprising: an illumination optical system thatilluminates the subject's eye; a photographing optical system thatincludes a focusing unit that focuses returning light from the subject'seye on an imaging unit; a focus index projection unit that is providedat the illumination optical system and configured to project a focusindex on the subject's eye; a first moving unit configured to move thefocus index projection unit to a position conjugate with the subject'seye; and a second moving unit configured to move the focusing unit to aposition at which the focus index projection unit and the imaging unitare conjugate with each other.
 7. The opthalmologic imaging apparatusaccording to claim 6, wherein the first and the second moving units area focus link mechanism that moves the focus index projection unit andthe focusing unit in conjunction with each other.
 8. The opthalmologicimaging apparatus according to claim 6, wherein the focus indexprojection unit further comprises: a focus index light source, and anopening portion that projects a light flux from the focus index lightsource onto the fundus of the subject's eye as a focus index image. 9.The opthalmologic imaging apparatus according to claim 6, furthercomprising: an input unit configured to input a photographing signal;and a control unit configured to control the first moving unit toretract the focus index projection unit out from an optical pathaccording to the photographing signal.
 10. An opthalmologic imagingapparatus that captures an image of a fundus of a subject's eye, theopthalmologic imaging apparatus comprising: an observation light sourceconfigured to generate observation light to illuminate the subject's eyevia an illumination optical system; a focus index projection unit thatis provided at the illumination optical system and configured to projecta focus index on the fundus of the subject's eye; an input unitconfigured to input a photographing signal; a control unit configured tomove the focus index projection unit out from an optical path accordingto the photographing signal; and an extraction unit configured toextract an area corresponding to an optic papilla of the fundus from thefundus image of the fundus based on the observation light according tomovement of the focus index projection unit out from the optical path.11. A method for an opthalmologic imaging to capture an image of afundus of a subject's eye, the method comprising: a first extractingstep for extracting, from a first fundus image photographed with a firstlight quantity, an image of a first area having intensity not less thanpredetermined intensity and an image of a second area other than thefirst area; a second extracting step for extracting an image of an areacorresponding to the first area from a second fundus image photographedwith a second light quantity based on the light quantity of the firstarea; a third extracting step for extracting an image of an areacorresponding to the second area from a third fundus image photographedwith a third light quantity based on the light quantity of the secondarea; and a combining step for combining the images which are extractedin the second and third extracting steps.
 12. The opthalmologic imagingmethod according to claim 11, wherein the second extracting stepincludes a first conjugating step for conjugating the fundus and animaging unit with each other before the second fundus image including anoptic papilla of the fundus is photographed, and the third extractingstep includes a second conjugating step for conjugating the fundus andthe imaging unit with each other before the third fundus image includinga lutea of the fundus is photographed.
 13. A computer-readable mediumhaving stored thereon a program that causes a computer to execute themethod according to claim 11.